> To run a stirling engine you need to burn something. Doesn't that kind of
> defeat the purpose.

It's EXTERNAL combustion and fuel can be almost anything you design it to 
work for. The extermal combustion would allow you to even burn gas (petrol) 
with fgar less pollution from eg nitrous oxides. Same CO2 fwiw.

> The problem with the technology is the cost, not
> the range. Get LiFePo4 batteries down to a reasonable price, even in their
> current configuration, and you'll have a winner.

> The problem is that Lithium with a battery management system is still 
> about
> $USD0.75/Wh. So a reasonable range battery pack (25 kWh and up) will still
> run about $USD 20k and up and will need to be replaced periodically.

100 km you suggested.
25 kWh.
That's 250 Wh/km.
Martin suggested 250 to 500 Wh/mile at around ton speeds so about right.

So, for $20k and up you get a 100 km town battery with limited life.

Hydrogen gives you about 30 kWh/kg, so for 25 kWh at 100% efficiency you 
need ~1 kg
Make that say 5 kg to allow 20% storage to output (easily in a Stirling's 
capability).
Add N:1 for storage.
Add Stirling mass.
Getting more power scales up the Stirling.
Getting more energy scales up the storage.

The 25 kWh battery system is probably going to weigh around 100 kg.

I'd say that it looks like there's a good chance that a Stirling engine 
based system could be made viable against LiIon with some advantages (and 
some disadvantages).


     Russell McMahon






>
>
>>
>> For example, if you forget to recharge the battery in the morning, the
>> engine can at least carry you to a nearby "electric" station.
>
> Nearby? Electric cars can plug in anywhere that has electricity, and in
> urban and suburban environments, that pretty much anywhere.
>
> The other point is that once electric cars become commonplace then 
> charging
> will become automatic. It's pretty easy to have an inductive pad that sits
> in the driveway under the car. So simply parking it will be enough to
> charge it.
>
> Finally if there is wholesale change occurs, then a logical extension will
> be charging directly from the roadway. Several studies on the process has
> been conducted by the California PATH project. A summary paper can be 
> found
> here:
>
> http://repositories.cdlib.org/cgi/viewcontent.cgi?article=1257&context=its/path
>
> Such electrification would facilitate long range electric vehicle travel
> and would depress the need for ultra long range battery systems.
>
> Finally there are simple, plentiful, powerful battery technologies that 
> can
> serve well in emergency capacities. Zinc/Air and Aluminum/Air batteries
> have even more power than lithium and are lightweight. The problem is that
> they are not rechargable. However, they can easily serve as emergency 
> power
> in the case that the primary battery system fails.
>
> The fundamental problem is that everyone seems to want new transportation
> systems to function exactly like the current system. Gasoline is as close
> to a magic liquid fuel as one will ever find. That's why the whole
> transporation economy is based upon it. But even though the price has
> temporarily gone down, it is a finite resource. Also the emmissions are an
> issue.
>
> New ways of transportation will be different than the current way. As long
> as the requirements remain the same (i.e. can be refuled in 5 minutes,
> 400-600 mile range, etc) there's not going to be any movement away until
> the gas pumps run dry.
>
> BAJ
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